1. Field of the Invention
This invention relates to a rolling bearing arrangement provided with a vibration damping device and a lubricating oil supply device and, more particularly, to improvements in such a rolling bearing arrangement in which vibration damping is accomplished by an oil film damper while supplying an appropriate amount of lubricating oil to the rolling bearing.
2. Description of the Prior Art
As a rolling bearing arrangement provided with an oil film damper for accomplishing vibration damping of a rolling bearing, there has been proposed one disclosed in Japanese Utility Model Publication No 61-134536 which relates to a ball bearing arrangement for a supercharger. In this conventional arrangement, so-called oil film dampers are respectively formed along the outer peripheries of a turbine side ball bearing and a compressor side ball bearing, thereby supporting the ball bearings in a bearing housing in a floating state. The oil film dampers and the ball bearings are adapted to be supplied with lubricating oil through an oil inlet opening formed in the bearing housing. More specifically, the oil inlet opening opens to an annular space which is formed between the bearing housing and an annular groove formed in an outer sleeve surrounding the ball bearing. Accordingly, lubricating oil supplied from the oil inlet opening into the bearing housing is introduced to the annular space.
A part of the thus introduced lubricating oil is fed oil film dampers which are adjacent to the annular space and positioned on the opposite sides of the annular space in the axial direction, thereby constituting the oil film damper under the action of the thus fed lubricating oil. The oil film damper supports the ball bearings and therefore the rotatable turbine shaft of the supercharger in a floating state, thus suppressing vibration of the turbine shaft. The remaining part of the lubricating oil supplied to the annular space is fed to the ball bearing through a small diameter passage thereby achieving lubrication and cooling of the ball bearing. Thus, in the conventional rolling bearing arrangement, lubricating oil introduced from oil supply opening of the bearing housing to the annular space is distributed in parallel for the oil film damper and for lubrication of the ball bearing, and therefore it is difficult to simultaneously realize a sufficient vibration damping performance and optimizing of the lubricating oil supply amount to the ball bearing, a suitable control of distribution of the lubricating oil.
In other words, vibration damping performance is degraded if the lubricating oil supply amount to the ball bearing is adjusted after adjustment to obtain a required vibration damping performance, whereas it is difficult to supply an optimum amount of lubricating oil to the ball bearings if an adjustment for obtaining the required vibration damping performance is made after adjustment of the lubricating oil supply amount to the ball bearings to an optimum value. Thus, it is difficult to simultaneously meet both the requirements of oil flow for vibration damping performance and for providing a lubricating supply amount to the ball bearing.